In case of design of an optical network, the number of optical paths, used bands, channels of optical fibers, and the like that are accommodated in a network (NW) are designed by an optical path accommodation design technique. In this case, the number of optical paths, used bands, channels of optical fibers, and the like are designed every “node”, and then accommodation design on how communication equipment is positioned is performed. Herein, in the case of OTN (Optical Transfer Network) accommodation design, for example, an optical path is a path of HO-ODU (Higher-Order Optical channel Data Unit).
FIG. 13 is an explanation diagram illustrating an example of a node that includes shelves whose hardware capacity is unlimited. A hardware capacity is a quantity of hardware and a volume of a case that are accommodated in shelves, for example. A node 200 illustrated in FIG. 13 includes shelves 201. The shelf 201 includes network-side (NW-side) communication cards 202 such as optical transmitters/receivers, client-side (CL-side) communication cards 203 such as electrical transmitters/receivers, and a switch fabric (SWF) 204. The NW-side communication card 202 is connected to an optical path with a signal band of 10 Gbps or 100 Gbps (bits per second). For convenience of explanation, “Gbps” is simply referred to as “G”. The CL-side communication card 203 is connected to an electrical path with a signal band of 1.25G, 2.5G, or 10G. When the hardware capacity of the shelf 201 is unlimited, all the NW-side communication cards 202 and CL-side communication cards 203 can be accommodated in the one shelf 201. Therefore, accommodation design is not requested.
However, because the hardware capacity of the shelf 201 is actually limited, it is preferable that accommodation design is performed while considering all conditions such as the number of the shelves 201, the maximum volume of the shelf 201, a communication capacity between the shelves 201. Therefore, it is important to employ multi-shelf accommodation design in which the node 200 includes the shelves 201 whose hardware capacity is limited and the NW-side communication cards 202 and the CL-side communication cards 203 are accommodated in the shelf 201.
Because the shelf 201 is placed in a rack, it is desirable that the number of racks is one considering an occupied floor area of the rack. However, because it is actually required that the number of the shelves 201 is plural, it is required that the number of racks is plural considering the maximum number of shelves that can be accommodated in a rack.
In other words, multi-shelf accommodation design may be design on how the NW-side communication cards 202 and the CL-side communication cards 203 are accommodate in the shelf 201. It is noted that the NW-side communication cards 202 and the CL-side communication cards 203 are not directly stored in the shelf 201 but are accommodated in interface cards (IFC). The IFCs are accommodated in the shelf 201. Moreover, intercommunication between shelves occurs when the change (hereinafter, “transfer”) of connection between optical paths of Demand in NW, namely, transferring between the NW-side communication cards 202 is performed. Therefore, intercommunication between shelves requires IFC for shelf intercommunication.
Therefore, it is considered that multi-shelf accommodation design employs a greedy method that is used to solve a “box packing” problem for efficiently accommodating the NW-side communication cards 202 and the CL-side communication cards 203 in the shelf 201. A greedy method is a method for packing elements (IFC) having a large size until they are fully packed in a box (shelf), and adding a new box (shelf) at the time when elements are not packed any more, and again packing the elements in the new box (shelf).
Patent Literature 1: Japanese Laid-open Patent Publication No. H11-008641
However, because a design result is influenced by an order by which elements are packed even if multi-shelf accommodation design is performed by using a greedy method, it is difficult to be said that the number of shelves can be suppressed to the minimum.